Stern Propulsion Maneuvering for Sideways Ship Motion Without Yaw
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Solution Overview
Problem
Existing ship maneuvering systems, particularly those without a bow thruster, face challenges in maintaining position and maneuverability due to the limitations of dynamic positioning systems, especially when observation devices are affected by bow thruster operation, and require complex control operations to achieve transverse and pivot movements without turning.
Innovation Solution
A ship maneuvering system utilizing two propulsion systems at the stern, with port-side and starboard-side propulsion devices and rudders, employs a maneuvering control device to achieve transverse and pivot turning by balancing forces and turning moments between the two propulsion systems, allowing for easy operation using a joystick and dial inputs, enabling transverse, diagonal, and pivot movements without forward or backward motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bow thruster is used to improve maneuverability, then transverse movement capability is enhanced, but observation devices near the bow are affected and dynamic positioning cannot be performed during observation
Solution Approach 1:
The invention extracts the transverse movement function from the bow thruster and relocates it to the stern by utilizing the port-side and starboard-side propulsion systems. This allows the bow thruster to be excluded from operation during observation, eliminating the harmful impact on observation devices while maintaining maneuverability through alternative means.
Solution Approach 2:
The port-side and starboard-side propulsion systems, originally designed for primary propulsion, are made multi-functional by enabling them to perform both forward propulsion and transverse movement. This eliminates the need for separate bow thruster operation, allowing the same propulsion systems to handle both propulsion and maneuvering tasks without affecting observation devices.
2Reliability
If dynamic positioning system is used to maintain position, then position holding capability is improved, but the system becomes complex and requires bow thruster operation which affects observation
Solution Approach 1:
The invention makes the port-side and starboard-side propulsion systems multi-functional, enabling them to perform both primary propulsion and transverse movement for position holding. This eliminates the need for a separate bow thruster system, reducing overall system complexity while maintaining reliable position holding capability through coordinated control of the two propulsion systems.
Solution Approach 2:
The invention merges the transverse movement function with the primary propulsion function by using the same port-side and starboard-side propulsion systems for both tasks. This consolidation eliminates redundant systems and reduces complexity, while the coordinated control mechanism ensures reliable position holding capability is maintained.
3Speed
If transverse movement is achieved by differential propulsion force, then movement in desired direction is obtained, but turning moment is generated causing the ship to turn round instead of moving straight
Solution Approach 1:
The invention applies counterweight by generating an opposing turning moment through rudder adjustment to balance the turning moment produced by differential propulsion force. When the ship needs transverse movement, one propulsion system operates in reverse creating a turning moment, and the rudder is adjusted to generate an equal and opposite turning moment, canceling out the unwanted rotation and maintaining heading stability while enabling pure transverse movement.
Data Source
AI summary
A maneuvering system for a ship provided with, in the stern, a port-side propulsion system, and a starboard-side propulsion system. For controlling the system, a forward or backward force of the ship 1 is obtained by the difference between the forward and backward propulsion forces of the propulsion systems and a first turning moment in a turning direction of the ship generated by the propulsion forces is offset by a second turning moment in the turning direction of the ship generated by steering a port-side rudder, whereby the ship moves in a transversal manner toward its starboard side while rotation of the ship is avoided. A high degree of maneuverability is thereby achieved with a relatively simple maneuvering operation.